JP2003264887A - Spiral acoustic waveguide electroacoustical transducing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic waveguide and system for transmitting pressure wave energy produced by an electroacoustical transducer in a medium that propagates pressure wave energy. <P>SOLUTION: The acoustic waveguide and system includes a tube defining a spiral-shaped channel with a length of L. The tube has a first end and a second end with the first end closed and the second end open to the medium. The tube has a transducer opening for accommodating an electroacoustical transducer located between the first and second ends of the tube. The system includes an electroacoustical transducer mounted to the acoustic waveguide. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acoustic waveguide electroacoustic conversion system.

[0002]

By way of background, Bose, U.S. Pat. No. 4,62.
No. 8,528 and Bose US Pat. No. 6,278,78
Reference is made to No. 9 B1. The contents of both patents are hereby incorporated by reference.

[0003]

An important object of the present invention is to provide an improved acoustic waveguide and electroacoustic conversion system having long waveguide channels in a relatively compact structure.

[0004]

SUMMARY OF THE INVENTION In one aspect, the invention features an acoustic waveguide for transmitting pressure wave energy produced by an electroacoustic transducer in a medium for propagating the pressure wave energy. The acoustic waveguide has a tube that defines a helical channel of length L. The tube has a first end and a second end, and a transducer opening that houses an electroacoustic transducer located adjacent to the first end of the tube. The second end of the tube is open to the medium.

Embodiments can include one or more of the following features. The spiral channel can have a curvature with a smoothly varying radius. In addition, the inner walls of the waveguide can be adjacent to each other. Effective length of channel L
Can be approximately 1/4 the wavelength of the lowest frequency pressure wave energy transmitted by the waveguide. The lowest frequency to transmit corresponds substantially to the frequency at which the output level begins to drop substantially continuously with frequency. The tube can define a spiral channel having a rectangular cross section.
The tube can define a spiral channel having a rectangular cross section. The spiral channels defined by the tubes can be spiral wound in a single plane to form a flat spiral, or spiral in multiple planes to form a helical spiral.

Another aspect of the invention provides an acoustic waveguide for transmitting pressure wave energy produced by an electroacoustic transducer in a medium for propagating the pressure wave energy.
The waveguide has a spirally shaped tube having a first end and a second end. The first end of the tube is closed and the second end of the tube is open to the medium, and a transducer opening for accommodating an electroacoustic transducer is provided with the first and second ends of the tube. It is located on the tube in between. The tube includes a first spiral channel located between the transducer opening of the tube and a first end of the tube and an adjacent spiral channel located between the transducer opening of the tube and the second end of the tube. A second spiral channel is defined.

Embodiments can include one or more of the following features. The first spiral channel defined by the tube may have a length of 1 / 3L, while the second spiral channel may have a length of 2 / 3L. Adding 1 / 3L of the length of the first spiral channel and 2 / 3L of the length of the second spiral channel and an end effect results in about one wavelength of the pressure wave energy of the lowest frequency transmitted by the waveguide. It can be set to 1/4. First and second
The spiral channels can each have a curvature with a smoothly varying radius. The inner walls of the tube can be adjacent. The first spiral channel can have substantially the same cross section as the second spiral channel. The cross section of the first and second spiral channels may be rectangular. The tube can be made of PVC. Spirally winding a tube defining a spiral channel in a single plane,
A plane spiral can be formed. The tube can also be spirally wound in multiple planes to form a helical helix. A transducer housing can be attached to the tube, and the tube can have a second electroacoustic transducer opening located between the tube and the transducer housing. The tube can be a two part (part) structure and can be assembled using screws, bolts, clips, adhesives, glue, and the like.

In another aspect of the invention, a system for transmitting pressure wave energy in a medium that propagates the pressure wave energy is provided. The system includes an electroacoustic transducer having a vibrating surface and a spiral waveguide.

Embodiments of the invention may have one or more of the following advantages. The spiral waveguide can provide long waveguide channels in a relatively compact structure.
The long waveguide channel improves the bass response of the loudspeaker system, while the compact structure is particularly advantageous in loudspeaker systems where physical space is limited, such as automobiles and portable stereos. In addition, the spiral waveguide is 90 degrees or 18 degrees inside the channel.
Since it has no sharp bends of 0 degrees, undesired turbulence can be minimized in the waveguide channel. Also, the spiral waveguide has an open end and a closed end, and a transducer is arranged at a specific distance between the open end and the closed end, and the frequency response of the acoustic energy transmitted by the waveguide. It can also be configured to reduce the first peak at.

Other features, objects and advantages will be apparent from the following detailed description in connection with the accompanying drawings. Like reference symbols in the various drawings indicate like elements.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, FIG.
1A and 1B show top and bottom views, respectively, of the top (top) waveguide member 10, while FIGS. 1C and 1D respectively show the top surface of the matching (matching) bottom (bottom) waveguide member 11. A figure and a bottom view are shown. To form a spiral waveguide, the upper waveguide member 10 is attached to the lower waveguide member 11 to form a waveguide channel 20 having an open end 30 and a closed (closed) end 31 (length L).
To form. In this particular embodiment, the two waveguide members 10, 11 are attached by four screws passing through the four holes 41, 42, 43, 44. However, to attach the two waveguide members, screws,
Bolts, nails, clips, tabs and slots, tongues, pins, glue, glue, cement and the like may be used.

Referring again to FIGS. 1A and 1B, the upper waveguide member 10 has a transducer aperture 50 in which an electroacoustic transducer (transducer), such as a loudspeaker transducer (not shown). Can be attached.
In this particular embodiment, the lower waveguide member 11 comprises two holes 61, 62 to provide a wire passageway connecting the transducer to an electrical signal source. A transducer aperture 50 is provided along the waveguide channel 20 to divide the waveguide channel 20 into two adjacent channels, an open end channel 21 (length L ₁ ) and a closed end channel 22 (length L ₂ ). It is designed to be split. Both adjacent channels 21, 22 are
The radius has a curvature that changes smoothly (the curvature changes smoothly with radius), that is, it curves smoothly according to the radius, the rectangular cross sections are substantially equal, and they are centered on the same spiral axis.

Any end effect (e
plus the nd effect) is about a quarter of the wavelength of the lowest frequency pressure wave energy transmitted by the waveguide.
For example, if the lowest frequency pressure wave energy transmitted by the waveguide at room temperature in air is 60 Hz, the length of the waveguide channel 20 (plus all end effects) will be about 1.4 meters.

The walls of the waveguide channel 20 are rigid. PV
C, ABS, Lexan, other hard plastics, metals, wood, etc. are suitable materials for forming the walls of the waveguide.

The transducer may be mounted anywhere along the waveguide channel 20, depending on the design of the system. In the embodiment shown in FIGS. 1A-1D, the transducer aperture 50 is configured such that the path length of the open end channel 21 is about twice as long as the closed end channel 22 when the electroacoustic transducer is installed. . This transducer arrangement is useful for significantly reducing the first resonance peak appearing in the frequency response of acoustic energy transmitted by a single-ended waveguide.

2A and 2B show (i) a transducer placed close to the closed end of a waveguide channel of length L, and (ii) a transducer placed between the open and closed ends. However, when the distance between the open end and the transducer (2 / 3L) is about twice the distance between the closed end and the transducer (1 / 3L), the open end of the waveguide channel (FIG. 2A). )
3 is a graph of acoustic power output at the transducer aperture (FIG. 2B) as a function of frequency. In this particular example, the waveguide channels are about 1.34 meters long and have a circular cross-section with a cross-sectional diameter of 7.23 cm, which is about 56% of the cross-sectional area of the transducer. In this example, the space (volume) located behind the transducer and between the transducer and the waveguide channel is about 500 cubic centimeters. No space is required behind the transducer and between the transducer and the waveguide channel, in practice the mechanical dimensions of the transducer, the cross-section of the waveguide, and other design constraints allow If so, it is preferable that it is as small as possible (ideally 0). In this example, removing or reducing the space between the transducer and the waveguide channel does not lose the aforementioned effect (advantageous result) of reducing the first resonance peak.

As shown in FIG. 2A, the first resonance peak occurs at about 200 Hz in this example, and in order to reduce it significantly, a closed-ended channel with a length of 1 / 3L and a length of 2 / L.
Position the transducer where it splits the waveguide channel into a 3L open-ended channel (ie, a 2: 1 ratio). Similarly, FIG. 2B shows that at about 200 Hz, there is no corresponding null or zero in the transducer output (ie, reduced displacement).

3A-3E show another embodiment of a spiral waveguide electroacoustic conversion system. 3A and 3B show top and bottom views, respectively, of upper waveguide member 10, while FIGS. 3C and 3D respectively show top and bottom views of paired lower waveguide member 11. FIG. 3E shows a side view of the assembled spiral waveguide electroacoustic conversion system.

The waveguide shown in FIGS. 3A to 3E is similar to that shown in FIG.
Open end 30 and closed end 31 shown in FIGS.
The structure is similar to a waveguide having a spiral waveguide channel 20 with. The transducer opening 50 is the upper waveguide member 1
0 to connect the waveguide channel 20 to the open end channel 2
1 and adjacent closed end channel 22. The transducer aperture is located along the waveguide channel 20 such that the open end channel 21 is about twice as long as the closed end channel 22. In this embodiment, the size between the upper surface and the bottom surface of the assembled waveguide is reduced, and the structure is further downsized. For this purpose, the rear part of the converter is projected beyond the aforementioned bottom surface. The rear part of the converter described above
It is covered with the rear housing 70. The back housing 70 can be formed as an integral part of the lower waveguide member, or can be formed as a separate structure and attached to the rear portion of the lower waveguide member 11. The front side of the transducer faces out of the transducer opening 50. Figure 3A
In the embodiment shown in FIGS. 3 to 3E, a space is formed behind the transducer and between the transducer and the waveguide. From an acoustic performance standpoint, it is usually preferable to have as little space as possible behind the transducer and between the transducer and the waveguide, but design considerations such as limitations on the amount of physical space available in the waveguide. Other considerations may require space between the transducer and the transducer and the waveguide.

Some embodiments of the present invention have been described above. However, it will be appreciated that various modifications can be made without departing from the spirit and scope of the invention. For example, the embodiment shown in FIGS. 1A-1D and 3A and 3E has two adjacent spiral channels 2
A spiral waveguide structure having 1, 22 and radiating from a transducer aperture 50 is shown. However, another embodiment of the spiral waveguide has a single spiral channel radiating from the inner end to the outer end, and the electroacoustic transducer is mounted adjacent to the inner end (thus the single-ended waveguide is May be formed). Also, when installing the converter,
The oscillating plane of the transducer may be parallel to the plane of the spiral waveguide channel as shown in FIGS. 1A-1D and 3A-3E, or may be perpendicular to the plane of the spiral waveguide channel. , May be attached so that the vibrating surface is located at the end of the channel. Alternatively, the waveguide channels may be spirally wound in a single plane to form the spiral waveguide as a planar spiral (as shown in FIGS. 1A-1D and 3A-3E), or The waveguide channel is spirally wound in a plane of constant variation, so that the waveguide is helically spiral (ie, helix-shaped).
x)). The cross section of the waveguide channel is
It may be rectangular, circular, oval or the like. The length and cross section of the waveguide channel can be varied depending on the lowest desired frequency of transmission, the transmission medium, and the surface area of the transducer's vibrating surface. The transducer is partly or wholly surrounded by the waveguide structure, and it is not necessary for the front surface of the transducer to face the outside of the waveguide through-hole 50, for example mounted outside the aforementioned waveguide structure. The front surface of the converter may face the inside of the waveguide through hole 50. 1A to 1
The spiral acoustic waveguides shown in D and FIGS. 3A-3E show a two-part structure of a waveguide channel, the two-part structure comprising a single upper or lower member constituting the waveguide wall and substantially the same. May be made of a corresponding lower or upper member that is substantially flat and forms the fourth wall of the waveguide in combination with the upper or lower member, or the structure of the waveguide channel is a single-piece structure. Alternatively, they may be formed from a large number of parts and combined together. Yet another embodiment may include disposing a cushioning material, such as polyester, within the one or more waveguide channels.

It will be apparent to those skilled in the art that numerous changes can be made in the development of the particular apparatus and techniques disclosed herein without departing from the inventive concept. Accordingly, the invention resides in the device and techniques disclosed herein, or any novel feature that they possess.
And the combination of novel features shall be construed as being limited only by the spirit and scope of the claims.

[Brief description of drawings]

FIG. 1A is a top view of an upper spiral acoustic waveguide member with an electroacoustic transducer system having an open end and a closed end.

FIG. 1B is a bottom view of the upper spiral waveguide member of FIG. 1A.

FIG. 1C is a top view of a lower spiral waveguide member having an open end and a closed end.

FIG. 1D is a bottom view of the lower spiral waveguide member of FIG. 1C.

FIG. 2A shows the acoustic power output in frequency (i) at the end of a single-ended waveguide and (ii) at the end of an open-ended channel in a two-channel waveguide with a channel length ratio of 2: 1. It is a graph represented as a function.

FIG. 2B is a graph of (i) acoustic power output as a function of frequency in a single-ended waveguide and two-channel waveguide transducer with a channel length ratio of 2: 1.

FIG. 3A is a top view of an upper spiral waveguide member having an open end and a closed end and further having a transducer housing.

FIG. 3B is a bottom view of the upper spiral waveguide member of FIG. 3A.

FIG. 3C is a top view of a lower spiral waveguide member having an open end and a closed end and further having a transducer housing.

FIG. 3D is a bottom view of the lower spiral waveguide member of FIG. 3C.

3E is a side view when the upper spiral waveguide member shown in FIGS. 3A and 3B is attached to the lower waveguide member shown in FIGS. 3C and 3D.

[Explanation of symbols]

10 Upper waveguide member 11 Lower waveguide member 20 Waveguide channels 21 open end channel 22 closed end channel 30 open end 31 closed end 41, 42, 43, 44 holes 50 transducer aperture 61, 62 holes 70 Rear housing

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[Procedure amendment]

[Submission date] March 19, 2003 (2003.3.1)
9)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

FIG. 1A

FIG. 1B

[FIG. 1C]

[Figure 1D]

[FIG. 2A]

FIG. 2B

FIG. 3A

FIG. 3B

[Fig. 3C]

[Fig. 3D]

[FIG. 3E]

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D017 AD00                 5D018 AE13

Claims (39)

[Claims] 1. An acoustic waveguide for transmitting pressure wave energy generated by an electroacoustic transducer in a medium for propagating the pressure wave energy, the acoustic waveguide having a first end and a second end. A tube formed to define a helical channel of length L, adjacent to a first end of the tube, a transducer opening for accommodating an electroacoustic transducer is provided, An acoustic waveguide whose second end is open to the medium. 2. The acoustic waveguide according to claim 1, wherein the spiral channel has a curvature whose radius changes smoothly. 3. The acoustic waveguide according to claim 1, wherein the inner walls of the tube are adjacent to each other. 4. The acoustic waveguide of claim 1, wherein the length of the channel L plus the end effect is about 1/4 of the wavelength of the lowest frequency pressure wave energy transmitted by the waveguide. An acoustic waveguide. 5. The acoustic waveguide of claim 1, wherein the tube defines a spiral channel of rectangular cross section. 6. The acoustic waveguide of claim 1, wherein the tube defining the spiral channel is spirally wound in a single plane to form a planar helix. 7. The acoustic waveguide according to claim 1, wherein the tube defining the spiral channel is spirally wound in a plurality of planes to form a helical spiral. 8. An acoustic waveguide for transmitting pressure wave energy generated by an electroacoustic transducer in a medium for propagating pressure wave energy, the acoustic waveguide having a first end and a second end. A formed tube comprising a transducer opening between the first end and the second end of the tube, the transducer opening accommodating an electroacoustic transducer, the tube being a transducer of the tube A first spiral channel located between the opening and a first end of the tube, and an adjacent second spiral channel located between the transducer opening of the tube and the second end of the tube. Wherein the first end of the tube is closed and the second end of the tube is open. 9. The acoustic waveguide of claim 8, wherein the first spiral channel defined by the tube is 1 / 3L.
The acoustic waveguide having a length of 2/3 and the second spiral channel having a length of 2 / 3L. 10. The acoustic waveguide according to claim 8, wherein
The first spiral channel and the second spiral channel are
Acoustic waveguides each having a curvature whose radius changes smoothly. 11. The acoustic waveguide according to claim 8, wherein
An acoustic waveguide in which the inner walls of the tube are adjacent to each other. 12. The acoustic waveguide according to claim 8, wherein
If the length 2 / 3L of the second spiral channel is added to the length 1 / 3L of the first spiral channel, it becomes about 1/4 of the wavelength of the pressure wave energy of the lowest frequency transmitted by the waveguide. Become an acoustic waveguide. 13. The acoustic waveguide according to claim 8, wherein
An acoustic waveguide wherein the first spiral channel defined by the tube has a cross section that is substantially the same as the second spiral channel defined by the tube. 14. The acoustic waveguide of claim 13, wherein the first and second spiral channels are rectangular in cross section. 15. The acoustic waveguide according to claim 8, wherein
An acoustic waveguide in which the tube is made of hard plastic. 16. The acoustic waveguide according to claim 8, wherein
An acoustic waveguide in which the tube is spirally wound in a single plane to form a planar helix. 17. The acoustic waveguide according to claim 8, wherein
An acoustic waveguide in which the tube is spirally wound in a plurality of planes to form a helical spiral. 18. The acoustic waveguide according to claim 8, wherein:
An acoustic waveguide further comprising a transducer housing attached to the tube, the tube having a second electroacoustic transducer aperture located between the tube and the transducer housing. 19. The acoustic waveguide according to claim 8, wherein
The tube is an upper tube member having a top surface and a bottom surface, the top surface having the transducer opening, and the bottom surface being located between the transducer opening and a first end of the tube. A first spiral groove defining an upper portion of the first spiral channel, the bottom surface further adjoining the first spiral groove, the transducer opening and the second end of the tube. A second spiral groove defining an upper portion of the second spiral channel located between
An upper tube member, a lower tube member having a top surface and a bottom surface, the upper surface defining a lower portion of the first spiral channel located between the transducer opening and a first end of the tube. A second spiral defining a first spiral groove, the upper surface further adjoining the first spiral groove and located between the transducer opening and the second end of the tube. A lower tubular member having a second spiral groove defining a lower portion of the channel; and mounting a bottom surface of the upper tubular member on an upper surface of the lower tubular member, the first and second tubes of each member Aligning to form the first spiral channel and the second spiral channel,
Acoustic waveguide. 20. The acoustic waveguide of claim 19, further comprising a transducer housing attached to the tube, wherein a bottom surface of the lower tube member is located between the tube and the transducer housing. An acoustic waveguide having a second electroacoustic transducer opening. 21. The acoustic waveguide according to claim 19, wherein the upper pipe member is attached to the lower pipe member by screws. 22. The acoustic waveguide according to claim 19, wherein the upper pipe member is attached to the lower pipe member by an adhesive. 23. A system for transmitting pressure wave energy in a medium for propagating pressure wave energy, comprising: an electroacoustic transducer having a vibrating surface; and a spiral waveguide, wherein the spiral conductor The waveguide comprises a spirally wound tube having a first end and a second end, the tube defining a spiral channel of length L, wherein the first end of the tube is the electrical channel. A system adjacent to an acoustic transducer and having a second end of the tube open to the medium. 24. The system of claim 23,
The system wherein the spiral channel has a curvature with a smoothly varying radius. 25. The system of claim 23,
A system in which the inner walls of the tube are adjacent. 26. The system of claim 23,
The system wherein the length of the channel L plus the end effect is about 1/4 of the wavelength of the lowest frequency pressure wave energy transmitted by the waveguide. 27. The system of claim 23,
A system in which the tube defines a spiral channel of rectangular cross section. 28. A system for transmitting pressure wave energy in a medium for propagating pressure wave energy, comprising: an electroacoustic transducer having an oscillating surface; and a spiral waveguide, wherein the spiral conductor A waveguide having a first end and a second end, a spirally wound tube, acoustically coupled to the electro-acoustic transducer between the first and second ends of the tube. A tube having a transducer opening, the tube comprising a first spiral channel located between the transducer opening of the tube and a first end of the tube, the transducer opening of the tube and the tube. A second spiral channel located between and adjacent the second end, the first end of the tube closed and the second end of the tube open. 29. The system of claim 28,
The first spiral channel defined by the tube is 1/3
A system having a length of L and the second spiral channel having a length of 2 / 3L. 30. The system of claim 28,
An acoustic waveguide in which the inner walls of the tube are adjacent to each other. 31. The system according to claim 29,
If the length 2 / 3L of the second spiral channel is added to the length 1 / 3L of the first spiral channel, it becomes about 1/4 of the wavelength of the pressure wave energy of the lowest frequency transmitted by the waveguide. Become a system. 32. The system of claim 28,
The system wherein the first spiral channel defined by the tube has substantially the same cross section as the second spiral channel defined by the tube. 33. The system of claim 32,
A system wherein the first and second helical channels are rectangular in cross section. 34. A method of manufacturing a spiral waveguide, comprising: forming a first member having a top surface and a bottom surface, the top surface of the first member having a transducer opening. The bottom surface of the has at least one spiral tube,
Forming a second member having a top surface and a bottom surface, the top surface having at least one spiral groove;
The spiral groove is a mirror image of the spiral groove provided on the bottom surface of the first member, and the step of attaching the bottom surface of the first member and the top surface of the second member to the bottom surface of the first member. Forming a spiral channel by aligning the groove with a groove provided on the upper surface of the second member. 35. The method according to claim 34, wherein the bottom surface of the first member and the top surface of the second member are attached by screws. 36. The method of claim 34, wherein the bottom surface of the first member and the top surface of the second member are attached with an adhesive. 37. The acoustic waveguide according to claim 1, wherein
An acoustic waveguide wherein the waveguide comprises a first assembly forming three waveguide walls and a second assembly which is essentially a flat plate with a fourth waveguide wall closing the waveguide. . 38. The acoustic waveguide according to claim 8, wherein
An acoustic waveguide wherein the waveguide comprises a first assembly forming three waveguide walls and a second assembly which is essentially a flat plate with a fourth waveguide wall closing the waveguide. . 39. The system of claim 23,
A system wherein the waveguide comprises a first assembly forming three waveguide walls and a second assembly which is essentially a flat plate with a fourth waveguide wall closing the waveguide.